A method for producing an NdFeB sintered includes forming a layer containing Dy and/or Tb on the surface of an NdFeB sintered magnet base material and then performing a grain boundary diffusion process for diffusing Dy and/or Tb from the aforementioned layer through the crystal grain boundaries of the magnet base material into the magnet base material by heating the magnet base material to a temperature equal to or lower than the sintering temperature thereof. In this method: a) the content of a rare earth in a metallic state in the magnet base material is equal to or higher than 12.7 at %; b) the aforementioned layer is a powder layer formed by depositing a powder; and c) the powder layer contains Dy and/or Tb in a metallic state by an amount equal to or higher than 50 mass %.